Not applicable.
Not applicable.
1. Field of the Invention
The present invention relates generally to light fixtures, and more particularly to an adjustable height light fixture adaptable for use as a grow light.
2. Discussion of Related Art
The use of conventional fluorescent light fixtures for grow lights is well known. The fixtures commonly retain long tubular bulbs in a housing member positioned in proximity to growing plants to provide optimum illumination for germination and growth. Illumination and incidental heat from the light may be controlled through shading, on-off cycles, or simply by positioning the light more closely or further from the plants. Accordingly, some grow light systems provide a degree of flexibility in positioning the light fixture relative to the plants. However, there is as yet unknown to the present inventor a hanging tubular bulb grow light fixture that provides infinite overhead (vertical) adjustability. The adjustable height light fixture of the present invention provides such an advantage.
According to the present invention, there is provided an adjustable height grow light having infinite vertical adjustability with only the slightest force applied either to raise the light or to lower it. The preferred embodiments of the light include a light stand having vertical support members and horizontal feet and for stabilizing the stand, and a horizontal support member interposed between the vertical support members from which a light fixture hangs. A first line is routed over a first line axle and rotatable axle sleeve and a shared or common axle and axle sleeve, and a second line is routed over a second line axle and rotatable axle sleeve, and also over the shared axle sleeve. After passing over the shared axle sleeve, each of the lines is connected to a constant force ribbon torsion spring with a coupling block. The ribbon torsion spring is set within the horizontal support member on fourth fixed axle. In a second preferred embodiment the common axle sleeve and shaft are eliminated.
In each of the preferred embodiments, the constant force ribbon torsion spring is selected and fabricated to have a tension rating slightly exceeding the total weight of the light fixture and installed bulbs. This permits the fixture to be moved upwardly and downwardly with very little force and to remain securely in place at any of an infinite number of selected positions within its range without the use of position locking means. The fixture remains level due to the line scheme employed.